Radiation Oncology


External beam radiotherapy (EBRT) is a treatment method used for delivering high energy radiation to tumour so the cancer cells are destroyed while sparing the surrounding normal tissue.

The treatment is done using a machine called linear accelerator (LINAC). High-energy x-rays or electrons are produced by the LINAC and directed to the target with precision from various angles. Multi leaf collimators (MLCs) are made of thin lead leaves that move while the machine moves around the patient. The MLCs form shapes that fit precisely the target.

A team of radiation oncologist, medical physicist, dosimetrist and radiation therapist are working together to produce a highly refined plan and achieve high quality treatment. The planning of your treatment may take several days and there is usually a week delay between planning appointment and your first treatment appointment.

External Radiotherapy Techniques


A series of images are produced prior treatment to assure that patient’s position is exactly as it was at the time of the CT scan. This is done using a kV CT scanner attached to the LINAC that obtains real-time 3D images of the patient (called cone beam CT). Thus, IGRT aid the accuracy of beam direction since beam positioning can be checked and verified prior treatment delivery.


A 3D conformal radiation treatment shapes the radiation beams to closely fit the area of interest. This allows the exact targeting of the tumour and the delivery of minimal dose to the surrounding normal tissue.


IMRT is a type of conformal radiotherapy, which is used to treat complex treatment volumes. The basis of this technique is the use of intensity modulated beams that can provide various intensity levels of radiation. Thus, different doses of radiation are delivered across the tumour. This technique is planned using inverse planning algorithms; ensuring conformity and dose homogeneity to the tumor while spearing close proximity organs at risk.


This is an advanced type of IMRT. The machine rotates around the patient during radiotherapy in an arc shape and continuously reshapes and changes the intensity of the radiation beam as it moves, enabling faster treatment delivery.


It is a highly precise technique for irradiation of intracranial tumors. It enables the delivery of high dose of radiotherapy with a very steep dose gradient outside the tumor. The high precision of the dose delivery resembles the precision of a surgical scalpel; this is why this technique is also referred as radiosurgery. It is an alternative to the surgical resection of brain metastases.


It is a non-invasive radiotherapy technique of high precision applied for extracranial tumors. It uses the same stereotactic principles as above, i.e few fractions, high dose per fraction, steep dose gradient. Adequate reproducible custom-made immobilisation devices, such as vacuum bags or masks, are necessary to reduce patient’s positioning deviation. Daily verification images are essential to ensure treatment accuracy. It is used mainly as an alternative for inoperable lung and liver metastases, for spine metastases and recently for the treatment of localized prostate cancer.


How radiation kills a tumor cell


Electrons are only used for superficial lesions since the depth of penetration to the underlying tissues and organs is limited.


Stereotactic Radiotherapy/Radiosurgery, which has been applied at the German Oncology Centre since it started its operation, requires high dosimetric and geometric accuracy in the administration of the high dose to the patient. As part of the personalized quality assurance for the administration of the therapeutic dose to each patient before the start of treatment, the German Oncology Center cooperates with RTSafe for the personalized PseudoPatientTM (510k FDA clearance) service. Before starting treatment, the exact anatomical model of the patient’s head is manufactured with 3D printing technology by RTSafe. The Radiation Oncologist and Medical Physics team selects specific locations within the target tumor as well as in adjacent sensitive healthy anatomical structures, where RTSafe will precisely measure the dose distribution from the actual treatment plan.

Prior to treatment, the personalized anatomical replica of the patient’s head, goes through all stages of the treatment process, it is placed on the surface of the Linear Accelerator and through imaging guidance the actual plan of the stereotactic Radiotherapy/Radiosurgery is delivered. The distribution of the dose at the designated points is measured, analyzed and compared with the treatment plan and thus, in addition to the other strict quality assurance methods in the Linear Accelerator, the accuracy of the patient’s treatment is confirmed in the most modern way. The results of this procedure form an integral part of the patient’s medical record. With this collaboration, the German Oncology Center enters the list of leading Centers for Radiation Oncology, which use RTSafe services around the world. It is worth noting that Personalized PseudoPatientTM was awarded as one of the 100 most important scientific innovations of 2019.

External Radiotherapy is carried out in special radioactive-protected rooms where high-energy X-Rays are aimed at the tumor using a machine called linear accelerator. Find more about our equipment here.

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